http://localhost:8081/jspui/handle/123456789/25 Mon, 30 Jun 2025 15:33:47 GMT 2025-06-30T15:33:47Z http://localhost:8081/jspui/handle/123456789/15998 Title: BEHAVIOUR OF CAISSON FOUNDATION UNDER STATIC AND SEISMIC CONDITIONS Authors: Kumar, Mohit Abstract: Bridges have been part of human civilization for many centuries now as they connect two locations separated by a river or any difficult terrain. Therefore, bridges facilitate trade, transportation and passage to locations which would otherwise be obscure and thus act as lifeline structures. Most bridges are supported by caissons which are massive and rigid foundation systems and is equipped to resist wide variety of loads like high magnitudes of vertical load, lateral load, uplift load and moments. Because of this virtue, caissons were supposed to be completely safe against any loading combination. However, The Great Hanshin earthquake of 1995 exposed the vulnerability of caissons against earthquake loads. An extensive literature review revealed several research gaps, such as lack of studies with consideration of combined failure wedge formed in front of caisson due to various resisting components, modified pseudo-dynamic study of caissons in layered soil, which could be addressed through the present study. Therefore, the present study attempts to study various aspects of caisson under static and seismic conditions. Fri, 01 Jul 2022 00:00:00 GMT http://localhost:8081/jspui/handle/123456789/15998 2022-07-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/15630 Title: NUMERICAL STUDY ON EMBANKMENTS RESTING ON LIQUEFIABLE SOIL WITH MITIGATION MEASURES Authors: Chakraborti, Abhijit Fri, 01 Sep 2023 00:00:00 GMT http://localhost:8081/jspui/handle/123456789/15630 2023-09-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/14763 Title: DEVELOPMENT OF AN APPROACH FOR BUILDING EXTRACTION USING SATELLITE IMAGES Authors: Susheela Abstract: The importance of increasing role of remote sensing and GIS technology in development of infrastructure has always posed varied challenges to the research community. Time and again, solutions have been provided by researchers for various matrices of physical built environment in different geographies. Amongst the several outcomes of the review of researches, one drawback in Indian context was that only limited studies had been carried out for fully automatic building extraction methods. It was also realized that established researches related to fully automatic building extraction methods were not tested for various types of buildings, but locally applied on construction materials. The identified gaps instigated to frame the objectivity of this research to develop a fully automated building extraction method confirming its applicability to Indian types of settlements. Based on the objectivity and target areas of these researches, each solution had its own strength and weaknesses and always left a scope for future research. In the present research, four building extraction methods were developed for which the required broad parameters were espoused from earlier researches. In first method, a threshold value was calculated for identification of buildings based on areas. The second method involved shadows and corner information for the extraction of buildings. The third extraction method was based on the texture to find the highest mean cluster value, to identify the cluster containing buildings. The fourth method involved the combination of threshold method and texture method. For verification of this method, the shadow mask was applied to detect true buildings and remove false positives. All the four developed methods accept raw images and as such no preprocessing was required before using the image in the developed program. However, in all the methods, post processing has been done to fill the small holes present in the extracted building areas, to smoothen the edges and to remove very small artifacts extracted as buildings. To test the developed methods for varied types and grouping of building in Indian settlement, the city of Jaipur in the state of Rajasthan, India, was chosen as the study area. Testing the proposed approach for complex variations in built environment and settlement formed the basis for choice of study area. The accuracy assessment of the results of developed methods was done three folds. Firstly, it was done on the basis of visual interpretation. Secondly, by comparing the ground truth produced by manually delineating the building boundaries in ArcGIS environment and the ii buildings extracted by developed methods. And thirdly, by comparing the OAP obtained from the supervised classification with the ones attained from the extracted buildings. The best texture combination was selected on the basis of ‘time taken’ and the ‘% error rate’ of area extracted. Analyzing the output results, it was observed that the method based on threshold value successfully extracted all types of buildings, but the shapes of the buildings were not retained. Also, the buildings close to each other were grouped together and extracted as one building. This method also resulted in some ‘False Positives’ and ‘False Negatives’, depending on the spectral reflectance values. The method based on shadow and corner information was not able to extract the buildings having complex shapes, and also the buildings without shadow associated with them. The method based on texture successfully extracted all types of buildings but resulted in high % error rate of area. As the number of texture methods increased in the combination, the % error decreased but the time taken for completing the extraction process also increased. However, using combination of Laws, Wavelet and GLCM, texture methods produced comparatively less % error and took less time to complete the extraction process. The method based on threshold, texture and shadow extracted all types of buildings successfully. All texture combinations used in this method gave higher accuracy than the accuracy obtained from supervised classification. Also, the % error rate of the area extracted was very less for all texture combinations. On comparison of four developed methods, it was found that the method based on threshold, texture and shadow produced best results for all types of building irrespective of their shapes, sizes and Orientation. This method also gave best results for slum buildings over other methods and extracted most of the slum buildings. The output of the research can be summarized that a fully automatic building extraction method has been developed for the complex settlement tested for an Indian case. The strength of this method is that no skills of remote sensing, Geographical Information System (GIS) or software development are required for its application, thus confirming it to be cost effective, time efficient and user friendly. Since, it is an initial attempt to develop a fully automatic building extraction method in Indian context, future researches are advised to test its application in various geographies and suggest the improvements to improve accuracy of extraction of ground features. Wed, 01 Jul 2015 00:00:00 GMT http://localhost:8081/jspui/handle/123456789/14763 2015-07-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/14742 Title: GEOSPATIAL MODELING OF SNOW-MET PARAMETERS AND ESTIMATION OF ENERGY FLUXES Authors: Gusain, Hemendra Singh Abstract: Surface energy fluxes of the cryospheric regions have many applications in climatology, hydrology, glaciology, snow avalanche forecasting and other snow/ice related studies. The components of the surface energy fluxes are net shortwave radiation flux, net longwave radiation flux, sensible heat flux, latent heat flux and sub surface heat flux. A number of snow-meteorological parameters may be used in estimation of these components of surface energy fluxes. These include air temperature, surface temperature, relative humidity, wind speed, atmospheric pressure, snow depth, albedo, cloud amount etc.. Cryospheric regions have limitations of poor monitoring using sparse in situ snow-met observations, which may therefore not characterize spatial variation of energy fluxes over a large snow/ice covered regions. Attempts are being made to model snow-met parameters at spatial scale and to estimate surface energy fluxes of large snow/ice covered regions using satellite remote sensing in conjunction with in situ observations. The present research focuses on geo-spatial modeling of snow depth, albedo, surface temperature and estimate surface energy fluxes using in situ as well as remote sensing observations for the snow/ice covered cryospheric regions of Antarctica and Western Himalaya. The work carried out in this thesis consists of three parts. The first part covers the geospatial modeling of few snow-met parameters e.g. snow depth, albedo and surface temperature. The second part focuses on the estimation of surface energy fluxes using in situ recorded snow-met data and presents analysis of the temporal variability of energy fluxes for four years. The third part presents the spatial estimation of surface energy fluxes, their evaluation using in situ recorded data and analysis of spatial variation in north and south aspect slopes in the mountain topography. A novel algorithm for geospatial interpolation of snow depth in Western Himalaya has been developed using snow depth data of manual observatories and digital elevation model. The algorithm improves upon the limitations of earlier published snow depth interpolation algorithm. The algorithm has been used to produce snow depth maps at spatial resolution of 0.5 km. These maps have been validated at few remote locations of the study area and an overall correlation coefficient of 0.71 and RMSE of 42 cm between estimated and in situ collected snow depth have been obtained. The proposed algorithm has advantages over the previous models of snow depth in Western Geospatial modeling of snow-met parameters and estimation of energy fluxes [ii] Himalaya by having higher spatial resolution and applicable for all snow thicknesses. Algorithms for direct retrieval of snow broadband albedo using AWiFS and MODIS data have been developed and presented. In situ measurements of spectral reflectance and transmitted solar irradiance using data collected from spectroradiometer in field have been used for the development of snow broadband albedo from narrow band AWiFS and MODIS data. The retrieved albedo from AWiFS and MODIS data has been validated with in situ measurements. The overall R2 and RMSE values between estimated and in situ recorded albedo values for AWiFS sensor have been observed as 0.94 and 0.03. The corresponding values for MODIS sensor have been observed as 0.88 and 0.026 respectively. The algorithm developed for estimation of broad band albedo using narrow band reflectance of AWiFS images is probably one of the first attempts in this direction. Another algorithm has been developed for the estimation of surface temperature in the study area of Antarctica using split-window technique. The R2 and RMSE of 0.99 and 0.8°C respectively have been obtained between estimated and in situ recorded surface temperature. Surface energy fluxes have been estimated using in situ as well as remote sensing data. In situ data have been used to estimate surface energy fluxes at the edge of the Antarctic ice sheet. A four-year analysis of the meteorological parameters, radiative and turbulent energy fluxes have been presented. The energy fluxes have been analysed for summer season, winter season and transition periods. It has been observed that the meteorological conditions at the observation site have generally been characterised by mild air temperature (annual mean -10.2 °C), low relative humidity (annual mean 50%) and high katabatic winds (annual mean 8.3 m s-1). Net radiative flux has been the main heat source to the glacier during summer (summer mean 46.8 Wm-2) and heat sink during winter (winter mean -42.2 Wm-2). Sensible heat flux (annual mean 32 Wm-2) has been the heat source and latent heat flux (annual mean -61 Wm-2) has been the heat sink to the glacier surface throughout the year. The study highlights the high latent heat flux at the edge of the ice sheet compared to other coastal locations in Dronning Maudland of Antarctica. This may be due to mild temperature, low relative humidity and high katabatic wind compared to other locations. High latent heat flux causes high sublimation rate equivalent to 5.29 cm w.eq per month at the study site. This may contribute to higher rate of ablation of the ice sheet at the location. Abstract [iii] Surface energy fluxes estimated using in situ recorded data do not characterize spatial variation of energy fluxes of large snow/ice covered regions. So, energy fluxes have been estimated at spatial level using MODIS data and in situ recorded snowmeteorological data in Western Himalaya and Antarctica. Incoming shortwave radiation flux and net shortwave radiation flux have been estimated at spatial resolution of 0.5 km whereas net longwave radiation flux and net radiation flux have been estimated at spatial resolution of 1.0 km. These estimated energy fluxes have been evaluated at sampled locations using automatic weather stations data. RMSE in estimation of incoming shortwave radiation flux, net shortwave radiation flux and net radiation flux have been found to be 75 W m-2, 84.9 W m-2, 90 W m-2 respectively in Western Himalaya and 105 W m-2, 75 W m-2, 81 W m-2 respectively in Antarctica. In this research, the incoming shortwave radiation flux has been estimated at higher spatial resolution than those reported in earlier studies and at a comparable accuracy of 14-27% of the mean values. As there is no access to data from any other source on spatial estimation of net shortwave radiation and net radiation fluxes for snow/ice covered region, the results of this study therefore have not been evaluated any further. Spatial and temporal variations of energy fluxes on north and south aspect slopes of mountain topography in Western Himalaya have also been assessed. Incoming shortwave radiation flux on south aspect slopes has been observed to be higher than those observed on north aspect slopes for the study period. This may be due to low incidence angle (i) of solar radiation on south aspect slopes as compared to that on the north aspect slopes. Temporal variation in the incoming shortwave radiation flux has been found to be in accordance with the variation of solar zenith angle. However, the temporal variation of net shortwave radiation flux has been found to depend on incoming shortwave radiation flux and the albedo of the snow cover. The significant findings of this research include, 1. Development of algorithm for geospatial interpolation of snow depth, which has advantages over the previously reported algorithms. The algorithm shall have direct applications in spatial estimation of sub-surface heat flux, avalanche forecasting, hydrological and glaciological studies. 2. Development of an algorithm for broad band albedo of snow cover from narrow bands reflectance of MODIS and AWiFS images. The algorithm can be used in various snow studies for estimating radiative energy fluxes and snowmelt run-off modeling. The Geospatial modeling of snow-met parameters and estimation of energy fluxes [iv] study has focused on estimation of the sublimation and melt of the ice sheet for four years using in situ recorded snow-met parameters. The study highlights the high ablation rate of the ice sheet near Schirmacher Oasis, compared to other parts of East Antarctica. 3. Estimation of surface energy fluxes at spatial level using remote sensing technique and validation with in situ recorded data. The results may be directly applicable to various snow/ice studies in the cryospheric regions. Sun, 01 Jun 2014 00:00:00 GMT http://localhost:8081/jspui/handle/123456789/14742 2014-06-01T00:00:00Z